The invention relates to an arrangement for detecting obstacles, particularly during the automatic closing of convertible tops, motor-vehicle windows or other closing device.
During the automatic closing of convertible tops or side windows of a motor vehicle, the danger exists that, for example, the hand of a person or another object can become pinched between the closing convertible top and the crossbeam of the windshield, or between the closing side window and the upper crossbeam of the window frame. Naturally, this can result not only in damaging the pinched object, but possibly also the appertaining parts of the closing device.
Therefore, the object of the present invention is to specify an arrangement for detecting obstacles of the type indicated at the outset, which in a simple manner, ensures differentiation between obstacles and the closing convertible top or side windows.
This objective is achieved according to the present invention in that a capacitive sensor device is provided, made up of an electrically conductive transmitter area on the one side and an electrically conductive sensor wire and at least one essentially potential-free metal area on the other side of an insulator, and that the transmitter area and the sensor wire are connected to an evaluation circuit.
The arrangement of the present invention offers the advantage that a simple geometric design can be implemented for the motor vehicle. It prevents objects from becoming pinched and, in response to danger, switches off the motor or does not permit a motor startup.
One advantageous refinement of the arrangement according to the present invention provides that the transmitter area, which is acted upon by an AC voltage, is arranged opposite the metal area which is set apart by the insulator and which has a suitably formed cutout for accommodating the sensor wire in the insulator, and that the sensor wire is connected to the evaluation circuit, at whose output a motor switching signal can be picked off for switching a drive motor.
In this context, it has proven to be particularly worthwhile that the evaluation circuit is composed of a current-to-voltage converter for emitting a measuring signal and a downstream phase-dependent rectifier arrangement supplied with the AC voltage and the measuring signal, and that at the output of the phase-dependent rectifier arrangement, the motor switching signal can be picked off with a first level for enabling the drive motor, and with a second level for switching off the drive motor in response to the appearance of obstacles in the vicinity of the sensor device.
To prevent interference, it has proven to be particularly advantageous that the phase-dependent rectifier arrangement includes a phase shifter, at whose input the AC voltage is applied as reference signal, and whose output is connected to an input of two respective threshold circuits for the shunting of switching voltages, whose respective outputs are connected to a control input of two respective analog switches, and that the measuring signal is fed directly to the one analog switch and is fed inverted to the other analog switch, and that the output of each analog switch is connected to an input of an adding stage at whose output the motor switching signal can be picked off via a low-pass filter.
One particularly advantageous refinement of the present invention proposes that the sensor device for detecting obstacles during the closing of the convertible top be integrated in the crossbeam above the windshield of the motor vehicle.
In another advantageous variant of the invention, the sensor device for detecting obstacles during the closing of the side windows is integrated in the upper crossbeam of the window frames.
The insulator can be formed by a strip of suitable material. One particularly advantageous possibility for the design of the arrangement according to the present invention is to surround the sensor device with an elastic strip seal that also forms the insulator.